The tripod-type constant-velocity universal joint is one of the plunging-type constant-velocity universal joints, and hence is used at points for which angular displacement and axial displacement (plunging) are necessary. Examples thereof include a drive shaft for transmitting power from an engine to drive wheels, which is attached on the engine side of an intermediate shaft (shaft) constituting the drive shaft. Note that, a fixed-type constant-velocity universal joint which allows only angular displacement is attached on the drive wheel side of the shaft.
Well-known examples of the tripod-type constant-velocity universal joint include that of a single-roller type in which single rollers serving as torque transmitting elements are provided and that of a double-roller type in which double rollers are provided.
Well-known examples of the tripod-type constant-velocity universal joint of the double-roller type also include a tripod-type constant-velocity universal joint capable of suppressing vibration at the time of operation. FIG. 9 illustrates an example thereof, and FIG. 10 illustrates a lateral sectional view of FIG. 9 (sectional view taken in a direction orthogonal to an axial line of a joint) (Patent Document 1).
The tripod-type constant-velocity universal joint 101 includes a main portion constituted by an outer race 102 serving as an outer joint member, a tripod member 103 as an inner joint member having three journals 104 protruding in a radial direction, and roller units U serving as the torque transmitting elements.
The outer race 102 has a bottomed cylindrical shape of having an opening portion at one end thereof, and three linear track grooves 114 are equiangularly formed in the inner peripheral surface thereof. On the inside of the outer race 102, the tripod member 103 having the three journals 104 and the roller units U are accommodated. A center hole 110 is formed in the tripod member 103, and a shaft 109 is inserted into the center hole 110 and spline-fitted thereto. The shaft 109 is prevented from being detached from the center hole 110 of the tripod member 103 by means of an annular snap ring 111.
As illustrated in FIG. 11, each of the three journals 104 protruding on the tripod member 103 has, in lateral cross-section (cross-section taken in the direction orthogonal to the axial line of each of the journals), an elliptical shape longitudinal in a direction orthogonal to the axial line of the joint, and rotatably supports each of the roller units U. Further, each of the journals 104 has a straight shape (refer to FIGS. 9 and 10) in vertical cross-section (cross-section taken along a direction of the axial line of each of the journals).
The roller units U are accommodated in the track grooves 114 of the outer race 102 and moved in an axial direction by being guided along roller guide surfaces 108 of the track grooves 114. Further, each of the roller units U includes a main portion constituted by an outer roller 105, an inner roller 107 arranged on the inner peripheral surface of the outer roller 105 and fitted around each of the journals 104, and needle rollers 106 interposed between the outer roller 105 and the inner roller 107. As illustrated in FIGS. 9 and 10, by means of ring-shaped washers 112 and 113, the needle rollers 106 are prevented from being detached from each of the roller units U to the shaft 109 side or the inner peripheral surface side of the outer race 102. Note that, each of the journals 104 is held in contact with the inner roller 107 in the direction orthogonal to the axial line of the joint, that is, on the elliptically longitudinal side (most longitudinal parts of the ellipse), and has a gap 150 formed between each of the journals 104 and the inner roller 107 in the direction of the axial line of the joint.
DOCUMENT LIST
Patent Document
Patent Document 1: JP 2000-320563 A